Numerical investigation of existing RC exterior beam-column joints under cyclic loading: case study of 1971 algerian building

Many reinforced concrete (RC) buildings constructed in Algeria before the 1980s may have serious structural deficiencies and are considered substandard according to the Algerian seismic code. Specifically, the failure of the beam-column joints has been the cause of building collapse in many earthquakes in the past: Alasnam October 10, 1980 and Boumerdes May 21, 2003. In this work, the behavior of RC exterior beam-column joints under quasi-static cyclic loading is studied by 3D nonlinear finite element analysis using ANSYS software. To perform the non-linear analysis, the load was applied step by step and the modified Newton-Raphson method was used for the solution. In order to prove that the program successfully captures the necessary response parameters without any modifications to the structure details, some available experimental works were modeled and non-linearly analyzed using ANSYS. Moment-rotation and load-displacement relationships were compared with the experimental data. It was observed that the results are quite similar to each other. Thereafter, a typical RC exterior beam-column joint belonging to a building constructed for residential use in Algeria in 1971 was modeled using ANSYS. The joint was subjected to quasi-static cyclic loading, and its performance was examined in terms of load resistance and failure. The moment-rotation hysteresis curve has been established. The hysteretic loops of the joint, representing the existing structure, showed stiffness degradation and strength deterioration.